Initiator for incendiary pellet

ABSTRACT

This invention relates to an initiator for ignition and dispersal of a multiplicity of incendiary pellets from an impacting incendiary 40 mm cartridge. The initiator having a cylindrical combustible incendiary housing, an igniter housing charge operatively positioned in the cylindrical housing, a frangible wall means fixedly attached to the housing, a plurality of incendiary output pellets annularly positioned within the frangible means, means for trajectory improvement fixedly attached to the frangible wall means, and means for fuzing threadedly attached to the housing and intermediate to the trajectory improvement means and the plural incendiary output pellets. The initiator first ignites the igniter housing charge and the incendiary output pellets upon impact of the cartridge, and then secondly a short time thereafter disperses the ignited incendiary output pellets and distributes them for maximum effectiveness against a combustible target area.

1 June 10, 1975 United States Patent 1191 Nord et al.

[ INITIATOR FOR INCENDIARY PELLET Primary Examiner-Verlin R. PendegrassInventors: Kermit Nord Harvest, Ala.; Francis C. wanenhorist, CoonRapids Minn. Arromey, Agent, or Firm-Nathan Edelberg; Robert P.

Gibson; Max Yarmovsky The United States of America as [73] Assignee:

ABSTRACT represented by the Secretary of the Army, Washington, DC

This invention relates to an initiator for ignition and 74 00 %H6 mi 1I. 6 m. mm M 0M1 1" 3 7 9 n" l "u 8 n" 2 Hm b 4 mm e 3 H m F 3 mm mun. 0HS N M C a d m. M m P m F A UhF UH NUT 2 2 555 ll. ill

means, means for trajectory improvement fixedly at tached to thefrangible wall means, and means for fuz [56] References Cited UNITEDSTATES PATENTS ing threadedly attached to the housing and intermediateto the trajectory improvement means and the plural incendiary outputpellets. The initiator first ignites the igniter housing charge and theincendiary output pellets upon impact of the cartridge, and thensecondly a short time thereafter disperses the ignited incendiary outputpellets and distributes them for maximum effectiveness against acombustible target area.

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1,054,114 11/1951 102/68 5 Claims, 2 Drawing Figures PATENTEDJUH I 0I915 CONFIDENTIAL INITIATOR FOR INCENDIARY PELLET GOVERNMENT INTERESTThe invention described herein may be manufac tured, used and licensedby or for the Government for governmental purposes without the paymentto us of any royalty thereon.

BACKGROUND OF THE INVENTION Various projectiles have been developed inthe past to have incendiary capability against personnel and combustiblemateriel. The prior art incendiary device fired from artilleryprojectiles were not primarily concerned with maximum utilization ofspace within the projectile because of their relatively large volume.Prior art projectiles requiring more than one fuze to perform the dualfunction of ignition and dispersal of the incendiary could readily beaccomplished within the given space limitations of these large shells.With the development of smaller, shoulder launched, 40 mm projectile,severe space limitations were imposed by the smaller volume. In orderfor the 40 mm incendiary projectile to maintain its maximum effectivecombustibility against an area, it is necessary to widely and uniformlydisperse the incendiary material against the target area while theincendiary is still burning. Prior art devices having multipledistributable incendiary pellets have utilized a fuzing device for theignition of the pellet and a separate fuze for rupturing of theprojectile wall and dispersal of the pellet. This prior art dual fuzingmeans in the 40 mm projectile reduces the pellet payload capability,making it less effective against a target and more costly to manufacturebecause of the added mechanical and/or electrical actuating meansnecessary to accomplish the ignition and dispersal functions. Thepresent invention overcomes the aforementioned deficiencies in the priorart devices by providing a satisfactory means for igniting anddispersing a multiplicity of incendiary pellets from a 40 mm projectilewithout the need for more than one fuzing means.

SUMMARY OF THE INVENTION The present invention relates to a projectilefor incendiary pellets contained in small caliber cartridge e.g. a 40 mmcartridge, which has dual incendiary and screening capability and whichis effective against personnel and combustible materiel. An impact fuzelocated in the ogive section of the cartridge activates an axiallyaligned burst charge which is held proximate thereto by a hollowcylindrical adapter assembly. The latter is operatively heldintermediate to the fuze and a hollow cylindrical cup shaped projectilebody which is incendiary and holds a main single igniter charge. Theadapter assembly has a plurality of circumferentially located portswhich provide communicating paths between the burster charge and thepellet igniters. A plurality of incendiary pellets are peripherallystacked in an annular space between the outer surface of the adapterassembly and the inner walls of a notched cylindrical skirt. Thecylindrical shaped pellets have their open igniter ends positioned sothat they face the circumferential adapter assembly igniter ports. Thenotched cylindrical skirt retains the pellets in their cylindricallystacked configuration during the launch. A central axial main chargebore is located proximate to the main charge and contains therein a pairof pellet igniters for the main charge incendiary. An ogive protects thefuze in the forward end and helps to give the projectile an improvedballistic trajectory. The ogive is crimped to the outer circumference ofa cup shaped hollow collar open end. The notched skirt is crimped to theother end of the partially closed collar. A hollow cylindricalprojectile body when ignited acts as a single incendiary. The projectilebody is fixedly held within the other end of the notched skirt.

One of the objects of this invention is to provide an initiator for aplurality of incendiary pellets dispersed by a 40 mm projectile.

Another object of this invention is to provide a 40 mm projectile havingincendiary pellets which can be initiated and dispersed after impact bya single fuzing means.

Another object of this invention is to provide a 40 mm incendiaryprojectile which is effective against both personnel and combustiblemateriel.

Another object of this invention is to provide an incendiary projectilewhich is effective against personnel and combustible materiel which canbe launched from a held, shoulder fired weapon.

Another object of this invention is to provide a 40 mm incendiaryprojectile which is safe for storage, handling, transporting and firing.

Another object of this invention is to provide a 40 mm incendiaryprojectile which is compatible in size, weight and ballistic trajectoryof existing 40 mm ammunition.

Another object of this invention is that it should provide a 40 mmincendiary dual purpose projectile which is suitable for low cost massproduction.

Another object of this invention is that all the materials, of theloaded 40 mm incendiary projectile, in contact with each other should bemutually compatible.

While certain objects, features and advantages of the present inventionhave been specifically pointed out, others will become apparent from thefollowing description taken in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view and partialcross-sectional view taken along a plane through the longitudinal axisof the preferred embodiment of the initiator for the incendiary pelletsand main charge of a 40 mm projectile.

FIG. 2 is a cross-sectional view of the projectile illustrated in FIG. 1taken about line 22 showing the adapter assembly parts in relation tothe incendiary pellets.

Throughout the following description like reference numerals are used todenote like parts in the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 a hollowmagnesium projectile housing 10 has a cup shape side wall 12, a closedend 13 and a partially open top wall 16. The housing contains therein asingle main igniter charge 14. The top wall 16 of the projectile body 10has an axial threaded bore 18 therein. A hollow-cylindrical aluminumpellet skirt 20 has a plurality of circumferential notches 22 located inthe outer peripheral surface of the skirt wall 24. One open end of thepellet skirt 20 is fixedly attached to the projectile body side wall 12,the other open end is peripherally attached to one end of acylindrically flanged collar 26. The collar flange wall 28 supports animpact activated fuze 30 which is crimped to an adapted flange 32 of acylindrical adapter assembly 31. The adapter assembly tubular member 34has a burster charge central cylindrical bore 36 which communicates onone end with an impact fuze lead train detonator 38. The other end ofthe central bore 36 communicates with a smaller axial main chargeigniter bore 40 which retains therein two main charge igniter pellets 42and 42'. The other end of the adapter assembly 34 has a cylindricalexternally threaded extension 44 which operatively engages theprojectile body threaded bore 18. The main charge igniter pellets 42 and42' are held within the main charge igniter bore 40 by pressuresensitive tape 46. Intermediate to the igniter pellet 42 and the leadtrain 38 is the burster charge 48. A pair of burster pellets 49, 49' areoperatively positioned in the upper and lower halves of the burstercharge 48. A plurality of incendiary pellet ports 50 are radiallypositioned circumferentially around the adapter assembly central bore 36and communicates therewith. Intermediate a smooth inner skirt wall 25and the outer wall surface of the adapter assembly 34 are a plurality ofannularly stacked incendiary pellets S2, 52' and 52". An annularincendiary pellet channel 54 is intermediate to the adapter assemblyouter wall 35 and the open end of the cup shaped incendiary pelletsleeve 56 and communicates with the adapter assembly incendiary pelletports 50. An igniter pellet 58 partially fills the incendiary pelletsleeve 56 and has one face adjacent to the open end of the pelletsleeve. Intermediate to the igniter pellet mix 58 and the closed endofthe pellet sleeve 56 is igniter sleeve pellet 60. An ogive 62 has ablunt closed end 64 and an open end 66 which is crimped to the flangedcollar 26 at the collar open crimping end 27 forming a protective shieldfor the impact fuze 30 and giving the projectile the necessarystreamline contour for a good ballistic trajectory. The flanged endcollar end 28 is fixedly attached to the other open end of the notchedskirt 22.

In operation the aforedescribed device uses the same energy source tofirst cause ignition of the multiple incendiary output pellets 52, 52'and 52" and ignition of the single incendiary material 12 source maincharge igniter pellets 42, 42', and then to develop pressure for skirtwall 24 rupture so that the output pellets 52, 52' and 52" will beproperly distributed for maximum incendiary effect to an area target.

A suitable mixture for the igniter pellets 58, for the output pellets52, 52 and 52" and for the main charge igniter pellets 42, 42' and forthe burster pellets 49, 49' would consist of a mixture of bariumchromate 75 percent by weight having a particle size of 1.4 asdetermined by a Fisher Sub Sieve Sizer, boron 19 percent by weighthaving a particle size of 0.86, potassium perchlorate percent by weighthaving an 11.0 particle size, and a VAAR Binder manufactured by UnionCarbide having l percent by weight solid material residual afterevaporation A suitable mixture for the sleeve igniter pellets 60 wouldconsist of zirconium powder 65 percent by weight having a particle sizeof 2.5 t 1.0 micron, ferric oxide 25 percent by weight having a particlesize which will pass through a No. 325 sieve, and SUPERFLOSS asmanufactured by Johns Manville percent by weight having a specificgravity of 2.30, pH 9.0 passing through No. 325 sieve. A suitablemixture for the burster charge 48 to surround the burster pellets 49 and49 would be boron potassium nitrate. A suitable mixture for the singlemain igniter charge would consist of atomized aluminum 23 percent byweight.

5 iron oxide 75 percent by weight having a particle size which will passthrough a No. 325 sieve and a VAAR binder 2.0 percent solid residualafter evaporation as manufactured by Union Carbide.

Referring now to FIG. 2 the radially positioned incendiary pellets 52are shown intermediate the notched outer skirt wall 24 and the adapterassembly 34 having radially positioned incendiary pellet ports 50 whichlead into and communicate with the annular pellet channel 54.

From the above description it will be evident that the inventionprovides in the preferred embodiment an initiator for incendiary pelletswhich does not require separate fuzing means for ignition of theincendiary pellets and single charge impact incendiary and a fuzingmeans for the dispersion of the pellets thereby allowing the presentinvention to be incorporated with improved incendiary effectiveness intothe small hand held shoulder fired 40 mm cartridge.

We wish it to be understood that we do not desire to be limited to theexact detail of construction shown and described for obviousmodifications will occur to a person skilled in the art.

What is claimed is:

I. A multiple pellet dispensing incendiary cartridge which comprises:

a cylindrical housing incendiary material having a partially open endand a closed end; an igniter charge in said housing;

a hollow frangible wall means having open ends, wherein one of said endsis fixedly attached to said partially open housing end;

a plurality of incendiary means annularly positioned within saidfrangible means;

means for trajectory improvement fixedly attached to said otherfrangible wall means end; and

means for fuzing, threadedly attached to said housing partially open endand intermediate to said trajectory improvement means and said pluralincendiary means, for first igniting said igniter charge and saidincendiary means upon impact of said cartridge, and then secondly fordispersing said ignited incendiary means in a combustible target area.

2. An incendiary cartridge as recited in claim 1 wherein said frangiblewall means comprises:

a cylindrical aluminum tubing having an inner smooth wall and an outernotched wall.

3. An initiator for an incendiary cartridge as recited in claim 2wherein said incendiary means comprises;

a hollow cylindrical magnesium cup shaped sleeve having a closed end anda open end;

an igniter sleeve pellet operatively positioned within said sleeveadjacent to said closed end;

an igniter pellet operatively positioned within said sleeve intermediateto said sleeve pellet and said sleeve open end.

4. An incendiary cartridge as recited in claim 3 wherein said means fortrajectory improvement com- 5 prises:

a hollow ogival member having a blunt closed end and an open end oflarger diameter than said blunt end;

a hollow cylindrical cup shaped collar having an open end crimpedlyaffixed to said open ogival member end. and a flanged end fittahlyattached to said other frangible wall means end. S. An incendiarycartridge as recited in claim 4 wherein said means for fuzing comprises:

an impact fuze;

a lead train detonator operatively positioned within said impact fuzeand responsive to said impact fuze;

an adapter assembly, having an adapter flange fixedly held intermediatesaid impact fuze and said collar

1. A multiple pellet dispensing incendiary cartridge which comprises: acylindrical housing incendiary material having a partially open end anda closed end; an igniter charge in said housing; a hollow frangible wallmeans having open ends, wherein one of said ends is fixedly attached tosaid partially open housing end; a plurality of incendiary meansannularly positioned within said frangible means; means for trajectoryimprovement fixedly attached to said other frangible wall means end; andmeans for fuzing, threadedly attached to said housing partially open endand intermediate to said trajectory improvement means and said pluralincendiary means, for first igniting said igniter charge and saidincendiary means upon impact of said cartridge, and then secondly fordispersing said ignited incendiary means in a combustible target area.2. An incendiary cartridge as recited in claim 1 wherein said frangiblewall means comprises: a cylindrical aluminum tubing having an innersmooth wall and an outer notched wall.
 3. An initiator for an incendiarycartridge as recited in claim 2 wherein said incendiary means comprises:a hollow cylindrical magnesium cup shaped sleeve having a closed end anda open end; an igniter sleeve pellet operatively positioned within saidsleeve adjacent to said closed end; an igniter pellet operativelypositioned within said sleeve intermediate to said sleeve pellet andsaid sleeve open end.
 4. An incendiary cartridge as recited in claim 3wherein said means for trajectory improvement comprises: a hollow ogivalmember having a blunt closed end and an open end of larger diameter thansaid blunt end; a hollow cylindrical cup shaped collar having an openend crimpedly affixed to said open ogival member end, and a flanged endfittably attached to said other frangible wall means end.
 5. Anincendiary cartridge as recited in claim 4 wherein said means for fuzingcomprises: an impact fuze; a lead train detonator operatively positionedwithin said impact fuze and responsive to said impact fuze; an adapterassembly, having an adapter flange fixedly held intermediate said impactfuze and said collar flange and an integral tubular member axiallyaligned with said adapter flange, said tubular member having a maincharge axial igniter bore, a burster charge located in a burster chargeaxial central bore larger in diameter than said igniter bore, and aplurality of radially positioned incendiary pellet ports whoselongitudinal axis lie in a plane perpendicular to the longitudinal axisof said cartridge, for first igniting respectively said igniter housingcharge and said incendiary peLlets and secondly subsequently dispersingsaid pellets.